Currently, there are used many electronic devices, such as a mobile phone, a notebook computer, a digital still camera, a digital video camera, and a PDA, which have secondary batteries capable of being charged repeatedly therein. A user charges the secondary battery by connecting an electronic device to a commercial power source. The secondary battery has a property that it remarkably deteriorates depending on the way of being charged. For example, the depth of discharge, the charging frequency, and the charging current of the secondary battery influences how much the secondary battery is deteriorated. The repetition of the charging/discharging in the state in which the depth of discharge is small deteriorates the secondary battery. Further, the charging with a large charging current also deteriorates the secondary battery.
Accordingly, as shown in Patent Literature 1, for example, there is suggested a charging apparatus for suppressing the deterioration of the secondary battery caused by the repetition of the charging/discharging in the state in which the depth of discharge is small. With the use of the technology of Patent Literature 1, even when there is an error in the voltage detection, the deterioration of the secondary battery caused by accidentally returning to the full charge state soon can be suppressed.